add u1db code (not as submodule)

4 files changed, 1648 insertions, 0 deletions

diff --git a/u1db/backends/__init__.py b/u1db/backends/__init__.py
new file mode 100644
index 00000000..c8e5adc6
--- /dev/null
+++ b/u1db/backends/__init__.py
@@ -0,0 +1,211 @@
+# Copyright 2011 Canonical Ltd.
+#
+# This file is part of u1db.
+#
+# u1db is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License version 3
+# as published by the Free Software Foundation.
+#
+# u1db is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with u1db.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Abstract classes and common implementations for the backends."""
+
+import re
+try:
+    import simplejson as json
+except ImportError:
+    import json  # noqa
+import uuid
+
+import u1db
+from u1db import (
+    errors,
+)
+import u1db.sync
+from u1db.vectorclock import VectorClockRev
+
+
+check_doc_id_re = re.compile("^" + u1db.DOC_ID_CONSTRAINTS + "$", re.UNICODE)
+
+
+class CommonSyncTarget(u1db.sync.LocalSyncTarget):
+    pass
+
+
+class CommonBackend(u1db.Database):
+
+    document_size_limit = 0
+
+    def _allocate_doc_id(self):
+        """Generate a unique identifier for this document."""
+        return 'D-' + uuid.uuid4().hex  # 'D-' stands for document
+
+    def _allocate_transaction_id(self):
+        return 'T-' + uuid.uuid4().hex  # 'T-' stands for transaction
+
+    def _allocate_doc_rev(self, old_doc_rev):
+        vcr = VectorClockRev(old_doc_rev)
+        vcr.increment(self._replica_uid)
+        return vcr.as_str()
+
+    def _check_doc_id(self, doc_id):
+        if not check_doc_id_re.match(doc_id):
+            raise errors.InvalidDocId()
+
+    def _check_doc_size(self, doc):
+        if not self.document_size_limit:
+            return
+        if doc.get_size() > self.document_size_limit:
+            raise errors.DocumentTooBig
+
+    def _get_generation(self):
+        """Return the current generation.
+
+        """
+        raise NotImplementedError(self._get_generation)
+
+    def _get_generation_info(self):
+        """Return the current generation and transaction id.
+
+        """
+        raise NotImplementedError(self._get_generation_info)
+
+    def _get_doc(self, doc_id, check_for_conflicts=False):
+        """Extract the document from storage.
+
+        This can return None if the document doesn't exist.
+        """
+        raise NotImplementedError(self._get_doc)
+
+    def _has_conflicts(self, doc_id):
+        """Return True if the doc has conflicts, False otherwise."""
+        raise NotImplementedError(self._has_conflicts)
+
+    def create_doc(self, content, doc_id=None):
+        json_string = json.dumps(content)
+        if doc_id is None:
+            doc_id = self._allocate_doc_id()
+        doc = self._factory(doc_id, None, json_string)
+        self.put_doc(doc)
+        return doc
+
+    def create_doc_from_json(self, json, doc_id=None):
+        if doc_id is None:
+            doc_id = self._allocate_doc_id()
+        doc = self._factory(doc_id, None, json)
+        self.put_doc(doc)
+        return doc
+
+    def _get_transaction_log(self):
+        """This is only for the test suite, it is not part of the api."""
+        raise NotImplementedError(self._get_transaction_log)
+
+    def _put_and_update_indexes(self, doc_id, old_doc, new_rev, content):
+        raise NotImplementedError(self._put_and_update_indexes)
+
+    def get_docs(self, doc_ids, check_for_conflicts=True,
+                 include_deleted=False):
+        for doc_id in doc_ids:
+            doc = self._get_doc(
+                doc_id, check_for_conflicts=check_for_conflicts)
+            if doc.is_tombstone() and not include_deleted:
+                continue
+            yield doc
+
+    def _get_trans_id_for_gen(self, generation):
+        """Get the transaction id corresponding to a particular generation.
+
+        Raises an InvalidGeneration when the generation does not exist.
+
+        """
+        raise NotImplementedError(self._get_trans_id_for_gen)
+
+    def validate_gen_and_trans_id(self, generation, trans_id):
+        """Validate the generation and transaction id.
+
+        Raises an InvalidGeneration when the generation does not exist, and an
+        InvalidTransactionId when it does but with a different transaction id.
+
+        """
+        if generation == 0:
+            return
+        known_trans_id = self._get_trans_id_for_gen(generation)
+        if known_trans_id != trans_id:
+            raise errors.InvalidTransactionId
+
+    def _validate_source(self, other_replica_uid, other_generation,
+                         other_transaction_id):
+        """Validate the new generation and transaction id.
+
+        other_generation must be greater than what we have stored for this
+        replica, *or* it must be the same and the transaction_id must be the
+        same as well.
+        """
+        (old_generation,
+         old_transaction_id) = self._get_replica_gen_and_trans_id(
+             other_replica_uid)
+        if other_generation < old_generation:
+            raise errors.InvalidGeneration
+        if other_generation > old_generation:
+            return
+        if other_transaction_id == old_transaction_id:
+            return
+        raise errors.InvalidTransactionId
+
+    def _put_doc_if_newer(self, doc, save_conflict, replica_uid, replica_gen,
+                          replica_trans_id=''):
+        cur_doc = self._get_doc(doc.doc_id)
+        doc_vcr = VectorClockRev(doc.rev)
+        if cur_doc is None:
+            cur_vcr = VectorClockRev(None)
+        else:
+            cur_vcr = VectorClockRev(cur_doc.rev)
+        self._validate_source(replica_uid, replica_gen, replica_trans_id)
+        if doc_vcr.is_newer(cur_vcr):
+            rev = doc.rev
+            self._prune_conflicts(doc, doc_vcr)
+            if doc.rev != rev:
+                # conflicts have been autoresolved
+                state = 'superseded'
+            else:
+                state = 'inserted'
+            self._put_and_update_indexes(cur_doc, doc)
+        elif doc.rev == cur_doc.rev:
+            # magical convergence
+            state = 'converged'
+        elif cur_vcr.is_newer(doc_vcr):
+            # Don't add this to seen_ids, because we have something newer,
+            # so we should send it back, and we should not generate a
+            # conflict
+            state = 'superseded'
+        elif cur_doc.same_content_as(doc):
+            # the documents have been edited to the same thing at both ends
+            doc_vcr.maximize(cur_vcr)
+            doc_vcr.increment(self._replica_uid)
+            doc.rev = doc_vcr.as_str()
+            self._put_and_update_indexes(cur_doc, doc)
+            state = 'superseded'
+        else:
+            state = 'conflicted'
+            if save_conflict:
+                self._force_doc_sync_conflict(doc)
+        if replica_uid is not None and replica_gen is not None:
+            self._do_set_replica_gen_and_trans_id(
+                replica_uid, replica_gen, replica_trans_id)
+        return state, self._get_generation()
+
+    def _ensure_maximal_rev(self, cur_rev, extra_revs):
+        vcr = VectorClockRev(cur_rev)
+        for rev in extra_revs:
+            vcr.maximize(VectorClockRev(rev))
+        vcr.increment(self._replica_uid)
+        return vcr.as_str()
+
+    def set_document_size_limit(self, limit):
+        self.document_size_limit = limit
diff --git a/u1db/backends/dbschema.sql b/u1db/backends/dbschema.sql
new file mode 100644
index 00000000..ae027fc5
--- /dev/null
+++ b/u1db/backends/dbschema.sql
@@ -0,0 +1,42 @@
+-- Database schema
+CREATE TABLE transaction_log (
+    generation INTEGER PRIMARY KEY AUTOINCREMENT,
+    doc_id TEXT NOT NULL,
+    transaction_id TEXT NOT NULL
+);
+CREATE TABLE document (
+    doc_id TEXT PRIMARY KEY,
+    doc_rev TEXT NOT NULL,
+    content TEXT
+);
+CREATE TABLE document_fields (
+    doc_id TEXT NOT NULL,
+    field_name TEXT NOT NULL,
+    value TEXT
+);
+CREATE INDEX document_fields_field_value_doc_idx
+    ON document_fields(field_name, value, doc_id);
+
+CREATE TABLE sync_log (
+    replica_uid TEXT PRIMARY KEY,
+    known_generation INTEGER,
+    known_transaction_id TEXT
+);
+CREATE TABLE conflicts (
+    doc_id TEXT,
+    doc_rev TEXT,
+    content TEXT,
+    CONSTRAINT conflicts_pkey PRIMARY KEY (doc_id, doc_rev)
+);
+CREATE TABLE index_definitions (
+    name TEXT,
+    offset INT,
+    field TEXT,
+    CONSTRAINT index_definitions_pkey PRIMARY KEY (name, offset)
+);
+create index index_definitions_field on index_definitions(field);
+CREATE TABLE u1db_config (
+    name TEXT PRIMARY KEY,
+    value TEXT
+);
+INSERT INTO u1db_config VALUES ('sql_schema', '0');
diff --git a/u1db/backends/inmemory.py b/u1db/backends/inmemory.py
new file mode 100644
index 00000000..a271bb37
--- /dev/null
+++ b/u1db/backends/inmemory.py
@@ -0,0 +1,469 @@
+# Copyright 2011 Canonical Ltd.
+#
+# This file is part of u1db.
+#
+# u1db is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License version 3
+# as published by the Free Software Foundation.
+#
+# u1db is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with u1db.  If not, see <http://www.gnu.org/licenses/>.
+
+"""The in-memory Database class for U1DB."""
+
+try:
+    import simplejson as json
+except ImportError:
+    import json  # noqa
+
+from u1db import (
+    Document,
+    errors,
+    query_parser,
+    vectorclock,
+    )
+from u1db.backends import CommonBackend, CommonSyncTarget
+
+
+def get_prefix(value):
+    key_prefix = '\x01'.join(value)
+    return key_prefix.rstrip('*')
+
+
+class InMemoryDatabase(CommonBackend):
+    """A database that only stores the data internally."""
+
+    def __init__(self, replica_uid, document_factory=None):
+        self._transaction_log = []
+        self._docs = {}
+        # Map from doc_id => [(doc_rev, doc)] conflicts beyond 'winner'
+        self._conflicts = {}
+        self._other_generations = {}
+        self._indexes = {}
+        self._replica_uid = replica_uid
+        self._factory = document_factory or Document
+
+    def _set_replica_uid(self, replica_uid):
+        """Force the replica_uid to be set."""
+        self._replica_uid = replica_uid
+
+    def set_document_factory(self, factory):
+        self._factory = factory
+
+    def close(self):
+        # This is a no-op, We don't want to free the data because one client
+        # may be closing it, while another wants to inspect the results.
+        pass
+
+    def _get_replica_gen_and_trans_id(self, other_replica_uid):
+        return self._other_generations.get(other_replica_uid, (0, ''))
+
+    def _set_replica_gen_and_trans_id(self, other_replica_uid,
+                                      other_generation, other_transaction_id):
+        self._do_set_replica_gen_and_trans_id(
+            other_replica_uid, other_generation, other_transaction_id)
+
+    def _do_set_replica_gen_and_trans_id(self, other_replica_uid,
+                                         other_generation,
+                                         other_transaction_id):
+        # TODO: to handle race conditions, we may want to check if the current
+        #       value is greater than this new value.
+        self._other_generations[other_replica_uid] = (other_generation,
+                                                      other_transaction_id)
+
+    def get_sync_target(self):
+        return InMemorySyncTarget(self)
+
+    def _get_transaction_log(self):
+        # snapshot!
+        return self._transaction_log[:]
+
+    def _get_generation(self):
+        return len(self._transaction_log)
+
+    def _get_generation_info(self):
+        if not self._transaction_log:
+            return 0, ''
+        return len(self._transaction_log), self._transaction_log[-1][1]
+
+    def _get_trans_id_for_gen(self, generation):
+        if generation == 0:
+            return ''
+        if generation > len(self._transaction_log):
+            raise errors.InvalidGeneration
+        return self._transaction_log[generation - 1][1]
+
+    def put_doc(self, doc):
+        if doc.doc_id is None:
+            raise errors.InvalidDocId()
+        self._check_doc_id(doc.doc_id)
+        self._check_doc_size(doc)
+        old_doc = self._get_doc(doc.doc_id, check_for_conflicts=True)
+        if old_doc and old_doc.has_conflicts:
+            raise errors.ConflictedDoc()
+        if old_doc and doc.rev is None and old_doc.is_tombstone():
+            new_rev = self._allocate_doc_rev(old_doc.rev)
+        else:
+            if old_doc is not None:
+                if old_doc.rev != doc.rev:
+                    raise errors.RevisionConflict()
+            else:
+                if doc.rev is not None:
+                    raise errors.RevisionConflict()
+            new_rev = self._allocate_doc_rev(doc.rev)
+        doc.rev = new_rev
+        self._put_and_update_indexes(old_doc, doc)
+        return new_rev
+
+    def _put_and_update_indexes(self, old_doc, doc):
+        for index in self._indexes.itervalues():
+            if old_doc is not None and not old_doc.is_tombstone():
+                index.remove_json(old_doc.doc_id, old_doc.get_json())
+            if not doc.is_tombstone():
+                index.add_json(doc.doc_id, doc.get_json())
+        trans_id = self._allocate_transaction_id()
+        self._docs[doc.doc_id] = (doc.rev, doc.get_json())
+        self._transaction_log.append((doc.doc_id, trans_id))
+
+    def _get_doc(self, doc_id, check_for_conflicts=False):
+        try:
+            doc_rev, content = self._docs[doc_id]
+        except KeyError:
+            return None
+        doc = self._factory(doc_id, doc_rev, content)
+        if check_for_conflicts:
+            doc.has_conflicts = (doc.doc_id in self._conflicts)
+        return doc
+
+    def _has_conflicts(self, doc_id):
+        return doc_id in self._conflicts
+
+    def get_doc(self, doc_id, include_deleted=False):
+        doc = self._get_doc(doc_id, check_for_conflicts=True)
+        if doc is None:
+            return None
+        if doc.is_tombstone() and not include_deleted:
+            return None
+        return doc
+
+    def get_all_docs(self, include_deleted=False):
+        """Return all documents in the database."""
+        generation = self._get_generation()
+        results = []
+        for doc_id, (doc_rev, content) in self._docs.items():
+            if content is None and not include_deleted:
+                continue
+            doc = self._factory(doc_id, doc_rev, content)
+            doc.has_conflicts = self._has_conflicts(doc_id)
+            results.append(doc)
+        return (generation, results)
+
+    def get_doc_conflicts(self, doc_id):
+        if doc_id not in self._conflicts:
+            return []
+        result = [self._get_doc(doc_id)]
+        result[0].has_conflicts = True
+        result.extend([self._factory(doc_id, rev, content)
+                       for rev, content in self._conflicts[doc_id]])
+        return result
+
+    def _replace_conflicts(self, doc, conflicts):
+        if not conflicts:
+            del self._conflicts[doc.doc_id]
+        else:
+            self._conflicts[doc.doc_id] = conflicts
+        doc.has_conflicts = bool(conflicts)
+
+    def _prune_conflicts(self, doc, doc_vcr):
+        if self._has_conflicts(doc.doc_id):
+            autoresolved = False
+            remaining_conflicts = []
+            cur_conflicts = self._conflicts[doc.doc_id]
+            for c_rev, c_doc in cur_conflicts:
+                c_vcr = vectorclock.VectorClockRev(c_rev)
+                if doc_vcr.is_newer(c_vcr):
+                    continue
+                if doc.same_content_as(Document(doc.doc_id, c_rev, c_doc)):
+                    doc_vcr.maximize(c_vcr)
+                    autoresolved = True
+                    continue
+                remaining_conflicts.append((c_rev, c_doc))
+            if autoresolved:
+                doc_vcr.increment(self._replica_uid)
+                doc.rev = doc_vcr.as_str()
+            self._replace_conflicts(doc, remaining_conflicts)
+
+    def resolve_doc(self, doc, conflicted_doc_revs):
+        cur_doc = self._get_doc(doc.doc_id)
+        if cur_doc is None:
+            cur_rev = None
+        else:
+            cur_rev = cur_doc.rev
+        new_rev = self._ensure_maximal_rev(cur_rev, conflicted_doc_revs)
+        superseded_revs = set(conflicted_doc_revs)
+        remaining_conflicts = []
+        cur_conflicts = self._conflicts[doc.doc_id]
+        for c_rev, c_doc in cur_conflicts:
+            if c_rev in superseded_revs:
+                continue
+            remaining_conflicts.append((c_rev, c_doc))
+        doc.rev = new_rev
+        if cur_rev in superseded_revs:
+            self._put_and_update_indexes(cur_doc, doc)
+        else:
+            remaining_conflicts.append((new_rev, doc.get_json()))
+        self._replace_conflicts(doc, remaining_conflicts)
+
+    def delete_doc(self, doc):
+        if doc.doc_id not in self._docs:
+            raise errors.DocumentDoesNotExist
+        if self._docs[doc.doc_id][1] in ('null', None):
+            raise errors.DocumentAlreadyDeleted
+        doc.make_tombstone()
+        self.put_doc(doc)
+
+    def create_index(self, index_name, *index_expressions):
+        if index_name in self._indexes:
+            if self._indexes[index_name]._definition == list(
+                    index_expressions):
+                return
+            raise errors.IndexNameTakenError
+        index = InMemoryIndex(index_name, list(index_expressions))
+        for doc_id, (doc_rev, doc) in self._docs.iteritems():
+            if doc is not None:
+                index.add_json(doc_id, doc)
+        self._indexes[index_name] = index
+
+    def delete_index(self, index_name):
+        del self._indexes[index_name]
+
+    def list_indexes(self):
+        definitions = []
+        for idx in self._indexes.itervalues():
+            definitions.append((idx._name, idx._definition))
+        return definitions
+
+    def get_from_index(self, index_name, *key_values):
+        try:
+            index = self._indexes[index_name]
+        except KeyError:
+            raise errors.IndexDoesNotExist
+        doc_ids = index.lookup(key_values)
+        result = []
+        for doc_id in doc_ids:
+            result.append(self._get_doc(doc_id, check_for_conflicts=True))
+        return result
+
+    def get_range_from_index(self, index_name, start_value=None,
+                             end_value=None):
+        """Return all documents with key values in the specified range."""
+        try:
+            index = self._indexes[index_name]
+        except KeyError:
+            raise errors.IndexDoesNotExist
+        if isinstance(start_value, basestring):
+            start_value = (start_value,)
+        if isinstance(end_value, basestring):
+            end_value = (end_value,)
+        doc_ids = index.lookup_range(start_value, end_value)
+        result = []
+        for doc_id in doc_ids:
+            result.append(self._get_doc(doc_id, check_for_conflicts=True))
+        return result
+
+    def get_index_keys(self, index_name):
+        try:
+            index = self._indexes[index_name]
+        except KeyError:
+            raise errors.IndexDoesNotExist
+        keys = index.keys()
+        # XXX inefficiency warning
+        return list(set([tuple(key.split('\x01')) for key in keys]))
+
+    def whats_changed(self, old_generation=0):
+        changes = []
+        relevant_tail = self._transaction_log[old_generation:]
+        # We don't use len(self._transaction_log) because _transaction_log may
+        # get mutated by a concurrent operation.
+        cur_generation = old_generation + len(relevant_tail)
+        last_trans_id = ''
+        if relevant_tail:
+            last_trans_id = relevant_tail[-1][1]
+        elif self._transaction_log:
+            last_trans_id = self._transaction_log[-1][1]
+        seen = set()
+        generation = cur_generation
+        for doc_id, trans_id in reversed(relevant_tail):
+            if doc_id not in seen:
+                changes.append((doc_id, generation, trans_id))
+                seen.add(doc_id)
+            generation -= 1
+        changes.reverse()
+        return (cur_generation, last_trans_id, changes)
+
+    def _force_doc_sync_conflict(self, doc):
+        my_doc = self._get_doc(doc.doc_id)
+        self._prune_conflicts(doc, vectorclock.VectorClockRev(doc.rev))
+        self._conflicts.setdefault(doc.doc_id, []).append(
+            (my_doc.rev, my_doc.get_json()))
+        doc.has_conflicts = True
+        self._put_and_update_indexes(my_doc, doc)
+
+
+class InMemoryIndex(object):
+    """Interface for managing an Index."""
+
+    def __init__(self, index_name, index_definition):
+        self._name = index_name
+        self._definition = index_definition
+        self._values = {}
+        parser = query_parser.Parser()
+        self._getters = parser.parse_all(self._definition)
+
+    def evaluate_json(self, doc):
+        """Determine the 'key' after applying this index to the doc."""
+        raw = json.loads(doc)
+        return self.evaluate(raw)
+
+    def evaluate(self, obj):
+        """Evaluate a dict object, applying this definition."""
+        all_rows = [[]]
+        for getter in self._getters:
+            new_rows = []
+            keys = getter.get(obj)
+            if not keys:
+                return []
+            for key in keys:
+                new_rows.extend([row + [key] for row in all_rows])
+            all_rows = new_rows
+        all_rows = ['\x01'.join(row) for row in all_rows]
+        return all_rows
+
+    def add_json(self, doc_id, doc):
+        """Add this json doc to the index."""
+        keys = self.evaluate_json(doc)
+        if not keys:
+            return
+        for key in keys:
+            self._values.setdefault(key, []).append(doc_id)
+
+    def remove_json(self, doc_id, doc):
+        """Remove this json doc from the index."""
+        keys = self.evaluate_json(doc)
+        if keys:
+            for key in keys:
+                doc_ids = self._values[key]
+                doc_ids.remove(doc_id)
+                if not doc_ids:
+                    del self._values[key]
+
+    def _find_non_wildcards(self, values):
+        """Check if this should be a wildcard match.
+
+        Further, this will raise an exception if the syntax is improperly
+        defined.
+
+        :return: The offset of the last value we need to match against.
+        """
+        if len(values) != len(self._definition):
+            raise errors.InvalidValueForIndex()
+        is_wildcard = False
+        last = 0
+        for idx, val in enumerate(values):
+            if val.endswith('*'):
+                if val != '*':
+                    # We have an 'x*' style wildcard
+                    if is_wildcard:
+                        # We were already in wildcard mode, so this is invalid
+                        raise errors.InvalidGlobbing
+                    last = idx + 1
+                is_wildcard = True
+            else:
+                if is_wildcard:
+                    # We were in wildcard mode, we can't follow that with
+                    # non-wildcard
+                    raise errors.InvalidGlobbing
+                last = idx + 1
+        if not is_wildcard:
+            return -1
+        return last
+
+    def lookup(self, values):
+        """Find docs that match the values."""
+        last = self._find_non_wildcards(values)
+        if last == -1:
+            return self._lookup_exact(values)
+        else:
+            return self._lookup_prefix(values[:last])
+
+    def lookup_range(self, start_values, end_values):
+        """Find docs within the range."""
+        # TODO: Wildly inefficient, which is unlikely to be a problem for the
+        # inmemory implementation.
+        if start_values:
+            self._find_non_wildcards(start_values)
+            start_values = get_prefix(start_values)
+        if end_values:
+            if self._find_non_wildcards(end_values) == -1:
+                exact = True
+            else:
+                exact = False
+            end_values = get_prefix(end_values)
+        found = []
+        for key, doc_ids in sorted(self._values.iteritems()):
+            if start_values and start_values > key:
+                continue
+            if end_values and end_values < key:
+                if exact:
+                    break
+                else:
+                    if not key.startswith(end_values):
+                        break
+            found.extend(doc_ids)
+        return found
+
+    def keys(self):
+        """Find the indexed keys."""
+        return self._values.keys()
+
+    def _lookup_prefix(self, value):
+        """Find docs that match the prefix string in values."""
+        # TODO: We need a different data structure to make prefix style fast,
+        #       some sort of sorted list would work, but a plain dict doesn't.
+        key_prefix = get_prefix(value)
+        all_doc_ids = []
+        for key, doc_ids in sorted(self._values.iteritems()):
+            if key.startswith(key_prefix):
+                all_doc_ids.extend(doc_ids)
+        return all_doc_ids
+
+    def _lookup_exact(self, value):
+        """Find docs that match exactly."""
+        key = '\x01'.join(value)
+        if key in self._values:
+            return self._values[key]
+        return ()
+
+
+class InMemorySyncTarget(CommonSyncTarget):
+
+    def get_sync_info(self, source_replica_uid):
+        source_gen, source_trans_id = self._db._get_replica_gen_and_trans_id(
+            source_replica_uid)
+        my_gen, my_trans_id = self._db._get_generation_info()
+        return (
+            self._db._replica_uid, my_gen, my_trans_id, source_gen,
+            source_trans_id)
+
+    def record_sync_info(self, source_replica_uid, source_replica_generation,
+                         source_transaction_id):
+        if self._trace_hook:
+            self._trace_hook('record_sync_info')
+        self._db._set_replica_gen_and_trans_id(
+            source_replica_uid, source_replica_generation,
+            source_transaction_id)
diff --git a/u1db/backends/sqlite_backend.py b/u1db/backends/sqlite_backend.py
new file mode 100644
index 00000000..773213b5
--- /dev/null
+++ b/u1db/backends/sqlite_backend.py
@@ -0,0 +1,926 @@
+# Copyright 2011 Canonical Ltd.
+#
+# This file is part of u1db.
+#
+# u1db is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License version 3
+# as published by the Free Software Foundation.
+#
+# u1db is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with u1db.  If not, see <http://www.gnu.org/licenses/>.
+
+"""A U1DB implementation that uses SQLite as its persistence layer."""
+
+import errno
+import os
+try:
+    import simplejson as json
+except ImportError:
+    import json  # noqa
+from sqlite3 import dbapi2
+import sys
+import time
+import uuid
+
+import pkg_resources
+
+from u1db.backends import CommonBackend, CommonSyncTarget
+from u1db import (
+    Document,
+    errors,
+    query_parser,
+    vectorclock,
+    )
+
+
+class SQLiteDatabase(CommonBackend):
+    """A U1DB implementation that uses SQLite as its persistence layer."""
+
+    _sqlite_registry = {}
+
+    def __init__(self, sqlite_file, document_factory=None):
+        """Create a new sqlite file."""
+        self._db_handle = dbapi2.connect(sqlite_file)
+        self._real_replica_uid = None
+        self._ensure_schema()
+        self._factory = document_factory or Document
+
+    def set_document_factory(self, factory):
+        self._factory = factory
+
+    def get_sync_target(self):
+        return SQLiteSyncTarget(self)
+
+    @classmethod
+    def _which_index_storage(cls, c):
+        try:
+            c.execute("SELECT value FROM u1db_config"
+                      " WHERE name = 'index_storage'")
+        except dbapi2.OperationalError, e:
+            # The table does not exist yet
+            return None, e
+        else:
+            return c.fetchone()[0], None
+
+    WAIT_FOR_PARALLEL_INIT_HALF_INTERVAL = 0.5
+
+    @classmethod
+    def _open_database(cls, sqlite_file, document_factory=None):
+        if not os.path.isfile(sqlite_file):
+            raise errors.DatabaseDoesNotExist()
+        tries = 2
+        while True:
+            # Note: There seems to be a bug in sqlite 3.5.9 (with python2.6)
+            #       where without re-opening the database on Windows, it
+            #       doesn't see the transaction that was just committed
+            db_handle = dbapi2.connect(sqlite_file)
+            c = db_handle.cursor()
+            v, err = cls._which_index_storage(c)
+            db_handle.close()
+            if v is not None:
+                break
+            # possibly another process is initializing it, wait for it to be
+            # done
+            if tries == 0:
+                raise err  # go for the richest error?
+            tries -= 1
+            time.sleep(cls.WAIT_FOR_PARALLEL_INIT_HALF_INTERVAL)
+        return SQLiteDatabase._sqlite_registry[v](
+            sqlite_file, document_factory=document_factory)
+
+    @classmethod
+    def open_database(cls, sqlite_file, create, backend_cls=None,
+                      document_factory=None):
+        try:
+            return cls._open_database(
+                sqlite_file, document_factory=document_factory)
+        except errors.DatabaseDoesNotExist:
+            if not create:
+                raise
+            if backend_cls is None:
+                # default is SQLitePartialExpandDatabase
+                backend_cls = SQLitePartialExpandDatabase
+            return backend_cls(sqlite_file, document_factory=document_factory)
+
+    @staticmethod
+    def delete_database(sqlite_file):
+        try:
+            os.unlink(sqlite_file)
+        except OSError as ex:
+            if ex.errno == errno.ENOENT:
+                raise errors.DatabaseDoesNotExist()
+            raise
+
+    @staticmethod
+    def register_implementation(klass):
+        """Register that we implement an SQLiteDatabase.
+
+        The attribute _index_storage_value will be used as the lookup key.
+        """
+        SQLiteDatabase._sqlite_registry[klass._index_storage_value] = klass
+
+    def _get_sqlite_handle(self):
+        """Get access to the underlying sqlite database.
+
+        This should only be used by the test suite, etc, for examining the
+        state of the underlying database.
+        """
+        return self._db_handle
+
+    def _close_sqlite_handle(self):
+        """Release access to the underlying sqlite database."""
+        self._db_handle.close()
+
+    def close(self):
+        self._close_sqlite_handle()
+
+    def _is_initialized(self, c):
+        """Check if this database has been initialized."""
+        c.execute("PRAGMA case_sensitive_like=ON")
+        try:
+            c.execute("SELECT value FROM u1db_config"
+                      " WHERE name = 'sql_schema'")
+        except dbapi2.OperationalError:
+            # The table does not exist yet
+            val = None
+        else:
+            val = c.fetchone()
+        if val is not None:
+            return True
+        return False
+
+    def _initialize(self, c):
+        """Create the schema in the database."""
+        #read the script with sql commands
+        # TODO: Change how we set up the dependency. Most likely use something
+        #   like lp:dirspec to grab the file from a common resource
+        #   directory. Doesn't specifically need to be handled until we get
+        #   to the point of packaging this.
+        schema_content = pkg_resources.resource_string(
+            __name__, 'dbschema.sql')
+        # Note: We'd like to use c.executescript() here, but it seems that
+        #       executescript always commits, even if you set
+        #       isolation_level = None, so if we want to properly handle
+        #       exclusive locking and rollbacks between processes, we need
+        #       to execute it line-by-line
+        for line in schema_content.split(';'):
+            if not line:
+                continue
+            c.execute(line)
+        #add extra fields
+        self._extra_schema_init(c)
+        # A unique identifier should be set for this replica. Implementations
+        # don't have to strictly use uuid here, but we do want the uid to be
+        # unique amongst all databases that will sync with each other.
+        # We might extend this to using something with hostname for easier
+        # debugging.
+        self._set_replica_uid_in_transaction(uuid.uuid4().hex)
+        c.execute("INSERT INTO u1db_config VALUES" " ('index_storage', ?)",
+                  (self._index_storage_value,))
+
+    def _ensure_schema(self):
+        """Ensure that the database schema has been created."""
+        old_isolation_level = self._db_handle.isolation_level
+        c = self._db_handle.cursor()
+        if self._is_initialized(c):
+            return
+        try:
+            # autocommit/own mgmt of transactions
+            self._db_handle.isolation_level = None
+            with self._db_handle:
+                # only one execution path should initialize the db
+                c.execute("begin exclusive")
+                if self._is_initialized(c):
+                    return
+                self._initialize(c)
+        finally:
+            self._db_handle.isolation_level = old_isolation_level
+
+    def _extra_schema_init(self, c):
+        """Add any extra fields, etc to the basic table definitions."""
+
+    def _parse_index_definition(self, index_field):
+        """Parse a field definition for an index, returning a Getter."""
+        # Note: We may want to keep a Parser object around, and cache the
+        #       Getter objects for a greater length of time. Specifically, if
+        #       you create a bunch of indexes, and then insert 50k docs, you'll
+        #       re-parse the indexes between puts. The time to insert the docs
+        #       is still likely to dominate put_doc time, though.
+        parser = query_parser.Parser()
+        getter = parser.parse(index_field)
+        return getter
+
+    def _update_indexes(self, doc_id, raw_doc, getters, db_cursor):
+        """Update document_fields for a single document.
+
+        :param doc_id: Identifier for this document
+        :param raw_doc: The python dict representation of the document.
+        :param getters: A list of [(field_name, Getter)]. Getter.get will be
+            called to evaluate the index definition for this document, and the
+            results will be inserted into the db.
+        :param db_cursor: An sqlite Cursor.
+        :return: None
+        """
+        values = []
+        for field_name, getter in getters:
+            for idx_value in getter.get(raw_doc):
+                values.append((doc_id, field_name, idx_value))
+        if values:
+            db_cursor.executemany(
+                "INSERT INTO document_fields VALUES (?, ?, ?)", values)
+
+    def _set_replica_uid(self, replica_uid):
+        """Force the replica_uid to be set."""
+        with self._db_handle:
+            self._set_replica_uid_in_transaction(replica_uid)
+
+    def _set_replica_uid_in_transaction(self, replica_uid):
+        """Set the replica_uid. A transaction should already be held."""
+        c = self._db_handle.cursor()
+        c.execute("INSERT OR REPLACE INTO u1db_config"
+                  " VALUES ('replica_uid', ?)",
+                  (replica_uid,))
+        self._real_replica_uid = replica_uid
+
+    def _get_replica_uid(self):
+        if self._real_replica_uid is not None:
+            return self._real_replica_uid
+        c = self._db_handle.cursor()
+        c.execute("SELECT value FROM u1db_config WHERE name = 'replica_uid'")
+        val = c.fetchone()
+        if val is None:
+            return None
+        self._real_replica_uid = val[0]
+        return self._real_replica_uid
+
+    _replica_uid = property(_get_replica_uid)
+
+    def _get_generation(self):
+        c = self._db_handle.cursor()
+        c.execute('SELECT max(generation) FROM transaction_log')
+        val = c.fetchone()[0]
+        if val is None:
+            return 0
+        return val
+
+    def _get_generation_info(self):
+        c = self._db_handle.cursor()
+        c.execute(
+            'SELECT max(generation), transaction_id FROM transaction_log ')
+        val = c.fetchone()
+        if val[0] is None:
+            return(0, '')
+        return val
+
+    def _get_trans_id_for_gen(self, generation):
+        if generation == 0:
+            return ''
+        c = self._db_handle.cursor()
+        c.execute(
+            'SELECT transaction_id FROM transaction_log WHERE generation = ?',
+            (generation,))
+        val = c.fetchone()
+        if val is None:
+            raise errors.InvalidGeneration
+        return val[0]
+
+    def _get_transaction_log(self):
+        c = self._db_handle.cursor()
+        c.execute("SELECT doc_id, transaction_id FROM transaction_log"
+                  " ORDER BY generation")
+        return c.fetchall()
+
+    def _get_doc(self, doc_id, check_for_conflicts=False):
+        """Get just the document content, without fancy handling."""
+        c = self._db_handle.cursor()
+        if check_for_conflicts:
+            c.execute(
+                "SELECT document.doc_rev, document.content, "
+                "count(conflicts.doc_rev) FROM document LEFT OUTER JOIN "
+                "conflicts ON conflicts.doc_id = document.doc_id WHERE "
+                "document.doc_id = ? GROUP BY document.doc_id, "
+                "document.doc_rev, document.content;", (doc_id,))
+        else:
+            c.execute(
+                "SELECT doc_rev, content, 0 FROM document WHERE doc_id = ?",
+                (doc_id,))
+        val = c.fetchone()
+        if val is None:
+            return None
+        doc_rev, content, conflicts = val
+        doc = self._factory(doc_id, doc_rev, content)
+        doc.has_conflicts = conflicts > 0
+        return doc
+
+    def _has_conflicts(self, doc_id):
+        c = self._db_handle.cursor()
+        c.execute("SELECT 1 FROM conflicts WHERE doc_id = ? LIMIT 1",
+                  (doc_id,))
+        val = c.fetchone()
+        if val is None:
+            return False
+        else:
+            return True
+
+    def get_doc(self, doc_id, include_deleted=False):
+        doc = self._get_doc(doc_id, check_for_conflicts=True)
+        if doc is None:
+            return None
+        if doc.is_tombstone() and not include_deleted:
+            return None
+        return doc
+
+    def get_all_docs(self, include_deleted=False):
+        """Get all documents from the database."""
+        generation = self._get_generation()
+        results = []
+        c = self._db_handle.cursor()
+        c.execute(
+            "SELECT document.doc_id, document.doc_rev, document.content, "
+            "count(conflicts.doc_rev) FROM document LEFT OUTER JOIN conflicts "
+            "ON conflicts.doc_id = document.doc_id GROUP BY document.doc_id, "
+            "document.doc_rev, document.content;")
+        rows = c.fetchall()
+        for doc_id, doc_rev, content, conflicts in rows:
+            if content is None and not include_deleted:
+                continue
+            doc = self._factory(doc_id, doc_rev, content)
+            doc.has_conflicts = conflicts > 0
+            results.append(doc)
+        return (generation, results)
+
+    def put_doc(self, doc):
+        if doc.doc_id is None:
+            raise errors.InvalidDocId()
+        self._check_doc_id(doc.doc_id)
+        self._check_doc_size(doc)
+        with self._db_handle:
+            old_doc = self._get_doc(doc.doc_id, check_for_conflicts=True)
+            if old_doc and old_doc.has_conflicts:
+                raise errors.ConflictedDoc()
+            if old_doc and doc.rev is None and old_doc.is_tombstone():
+                new_rev = self._allocate_doc_rev(old_doc.rev)
+            else:
+                if old_doc is not None:
+                        if old_doc.rev != doc.rev:
+                            raise errors.RevisionConflict()
+                else:
+                    if doc.rev is not None:
+                        raise errors.RevisionConflict()
+                new_rev = self._allocate_doc_rev(doc.rev)
+            doc.rev = new_rev
+            self._put_and_update_indexes(old_doc, doc)
+        return new_rev
+
+    def _expand_to_fields(self, doc_id, base_field, raw_doc, save_none):
+        """Convert a dict representation into named fields.
+
+        So something like: {'key1': 'val1', 'key2': 'val2'}
+        gets converted into: [(doc_id, 'key1', 'val1', 0)
+                              (doc_id, 'key2', 'val2', 0)]
+        :param doc_id: Just added to every record.
+        :param base_field: if set, these are nested keys, so each field should
+            be appropriately prefixed.
+        :param raw_doc: The python dictionary.
+        """
+        # TODO: Handle lists
+        values = []
+        for field_name, value in raw_doc.iteritems():
+            if value is None and not save_none:
+                continue
+            if base_field:
+                full_name = base_field + '.' + field_name
+            else:
+                full_name = field_name
+            if value is None or isinstance(value, (int, float, basestring)):
+                values.append((doc_id, full_name, value, len(values)))
+            else:
+                subvalues = self._expand_to_fields(doc_id, full_name, value,
+                                                   save_none)
+                for _, subfield_name, val, _ in subvalues:
+                    values.append((doc_id, subfield_name, val, len(values)))
+        return values
+
+    def _put_and_update_indexes(self, old_doc, doc):
+        """Actually insert a document into the database.
+
+        This both updates the existing documents content, and any indexes that
+        refer to this document.
+        """
+        raise NotImplementedError(self._put_and_update_indexes)
+
+    def whats_changed(self, old_generation=0):
+        c = self._db_handle.cursor()
+        c.execute("SELECT generation, doc_id, transaction_id"
+                  " FROM transaction_log"
+                  " WHERE generation > ? ORDER BY generation DESC",
+                  (old_generation,))
+        results = c.fetchall()
+        cur_gen = old_generation
+        seen = set()
+        changes = []
+        newest_trans_id = ''
+        for generation, doc_id, trans_id in results:
+            if doc_id not in seen:
+                changes.append((doc_id, generation, trans_id))
+                seen.add(doc_id)
+        if changes:
+            cur_gen = changes[0][1]  # max generation
+            newest_trans_id = changes[0][2]
+            changes.reverse()
+        else:
+            c.execute("SELECT generation, transaction_id"
+                      " FROM transaction_log ORDER BY generation DESC LIMIT 1")
+            results = c.fetchone()
+            if not results:
+                cur_gen = 0
+                newest_trans_id = ''
+            else:
+                cur_gen, newest_trans_id = results
+
+        return cur_gen, newest_trans_id, changes
+
+    def delete_doc(self, doc):
+        with self._db_handle:
+            old_doc = self._get_doc(doc.doc_id, check_for_conflicts=True)
+            if old_doc is None:
+                raise errors.DocumentDoesNotExist
+            if old_doc.rev != doc.rev:
+                raise errors.RevisionConflict()
+            if old_doc.is_tombstone():
+                raise errors.DocumentAlreadyDeleted
+            if old_doc.has_conflicts:
+                raise errors.ConflictedDoc()
+            new_rev = self._allocate_doc_rev(doc.rev)
+            doc.rev = new_rev
+            doc.make_tombstone()
+            self._put_and_update_indexes(old_doc, doc)
+        return new_rev
+
+    def _get_conflicts(self, doc_id):
+        c = self._db_handle.cursor()
+        c.execute("SELECT doc_rev, content FROM conflicts WHERE doc_id = ?",
+                  (doc_id,))
+        return [self._factory(doc_id, doc_rev, content)
+                for doc_rev, content in c.fetchall()]
+
+    def get_doc_conflicts(self, doc_id):
+        with self._db_handle:
+            conflict_docs = self._get_conflicts(doc_id)
+            if not conflict_docs:
+                return []
+            this_doc = self._get_doc(doc_id)
+            this_doc.has_conflicts = True
+            return [this_doc] + conflict_docs
+
+    def _get_replica_gen_and_trans_id(self, other_replica_uid):
+        c = self._db_handle.cursor()
+        c.execute("SELECT known_generation, known_transaction_id FROM sync_log"
+                  " WHERE replica_uid = ?",
+                  (other_replica_uid,))
+        val = c.fetchone()
+        if val is None:
+            other_gen = 0
+            trans_id = ''
+        else:
+            other_gen = val[0]
+            trans_id = val[1]
+        return other_gen, trans_id
+
+    def _set_replica_gen_and_trans_id(self, other_replica_uid,
+                                      other_generation, other_transaction_id):
+        with self._db_handle:
+            self._do_set_replica_gen_and_trans_id(
+                other_replica_uid, other_generation, other_transaction_id)
+
+    def _do_set_replica_gen_and_trans_id(self, other_replica_uid,
+                                         other_generation,
+                                         other_transaction_id):
+            c = self._db_handle.cursor()
+            c.execute("INSERT OR REPLACE INTO sync_log VALUES (?, ?, ?)",
+                      (other_replica_uid, other_generation,
+                       other_transaction_id))
+
+    def _put_doc_if_newer(self, doc, save_conflict, replica_uid=None,
+                          replica_gen=None, replica_trans_id=None):
+        with self._db_handle:
+            return super(SQLiteDatabase, self)._put_doc_if_newer(doc,
+                save_conflict=save_conflict,
+                replica_uid=replica_uid, replica_gen=replica_gen,
+                replica_trans_id=replica_trans_id)
+
+    def _add_conflict(self, c, doc_id, my_doc_rev, my_content):
+        c.execute("INSERT INTO conflicts VALUES (?, ?, ?)",
+                  (doc_id, my_doc_rev, my_content))
+
+    def _delete_conflicts(self, c, doc, conflict_revs):
+        deleting = [(doc.doc_id, c_rev) for c_rev in conflict_revs]
+        c.executemany("DELETE FROM conflicts"
+                      " WHERE doc_id=? AND doc_rev=?", deleting)
+        doc.has_conflicts = self._has_conflicts(doc.doc_id)
+
+    def _prune_conflicts(self, doc, doc_vcr):
+        if self._has_conflicts(doc.doc_id):
+            autoresolved = False
+            c_revs_to_prune = []
+            for c_doc in self._get_conflicts(doc.doc_id):
+                c_vcr = vectorclock.VectorClockRev(c_doc.rev)
+                if doc_vcr.is_newer(c_vcr):
+                    c_revs_to_prune.append(c_doc.rev)
+                elif doc.same_content_as(c_doc):
+                    c_revs_to_prune.append(c_doc.rev)
+                    doc_vcr.maximize(c_vcr)
+                    autoresolved = True
+            if autoresolved:
+                doc_vcr.increment(self._replica_uid)
+                doc.rev = doc_vcr.as_str()
+            c = self._db_handle.cursor()
+            self._delete_conflicts(c, doc, c_revs_to_prune)
+
+    def _force_doc_sync_conflict(self, doc):
+        my_doc = self._get_doc(doc.doc_id)
+        c = self._db_handle.cursor()
+        self._prune_conflicts(doc, vectorclock.VectorClockRev(doc.rev))
+        self._add_conflict(c, doc.doc_id, my_doc.rev, my_doc.get_json())
+        doc.has_conflicts = True
+        self._put_and_update_indexes(my_doc, doc)
+
+    def resolve_doc(self, doc, conflicted_doc_revs):
+        with self._db_handle:
+            cur_doc = self._get_doc(doc.doc_id)
+            # TODO: https://bugs.launchpad.net/u1db/+bug/928274
+            #       I think we have a logic bug in resolve_doc
+            #       Specifically, cur_doc.rev is always in the final vector
+            #       clock of revisions that we supersede, even if it wasn't in
+            #       conflicted_doc_revs. We still add it as a conflict, but the
+            #       fact that _put_doc_if_newer propagates resolutions means I
+            #       think that conflict could accidentally be resolved. We need
+            #       to add a test for this case first. (create a rev, create a
+            #       conflict, create another conflict, resolve the first rev
+            #       and first conflict, then make sure that the resolved
+            #       rev doesn't supersede the second conflict rev.) It *might*
+            #       not matter, because the superseding rev is in as a
+            #       conflict, but it does seem incorrect
+            new_rev = self._ensure_maximal_rev(cur_doc.rev,
+                                               conflicted_doc_revs)
+            superseded_revs = set(conflicted_doc_revs)
+            c = self._db_handle.cursor()
+            doc.rev = new_rev
+            if cur_doc.rev in superseded_revs:
+                self._put_and_update_indexes(cur_doc, doc)
+            else:
+                self._add_conflict(c, doc.doc_id, new_rev, doc.get_json())
+            # TODO: Is there some way that we could construct a rev that would
+            #       end up in superseded_revs, such that we add a conflict, and
+            #       then immediately delete it?
+            self._delete_conflicts(c, doc, superseded_revs)
+
+    def list_indexes(self):
+        """Return the list of indexes and their definitions."""
+        c = self._db_handle.cursor()
+        # TODO: How do we test the ordering?
+        c.execute("SELECT name, field FROM index_definitions"
+                  " ORDER BY name, offset")
+        definitions = []
+        cur_name = None
+        for name, field in c.fetchall():
+            if cur_name != name:
+                definitions.append((name, []))
+                cur_name = name
+            definitions[-1][-1].append(field)
+        return definitions
+
+    def _get_index_definition(self, index_name):
+        """Return the stored definition for a given index_name."""
+        c = self._db_handle.cursor()
+        c.execute("SELECT field FROM index_definitions"
+                  " WHERE name = ? ORDER BY offset", (index_name,))
+        fields = [x[0] for x in c.fetchall()]
+        if not fields:
+            raise errors.IndexDoesNotExist
+        return fields
+
+    @staticmethod
+    def _strip_glob(value):
+        """Remove the trailing * from a value."""
+        assert value[-1] == '*'
+        return value[:-1]
+
+    def _format_query(self, definition, key_values):
+        # First, build the definition. We join the document_fields table
+        # against itself, as many times as the 'width' of our definition.
+        # We then do a query for each key_value, one-at-a-time.
+        # Note: All of these strings are static, we could cache them, etc.
+        tables = ["document_fields d%d" % i for i in range(len(definition))]
+        novalue_where = ["d.doc_id = d%d.doc_id"
+                         " AND d%d.field_name = ?"
+                         % (i, i) for i in range(len(definition))]
+        wildcard_where = [novalue_where[i]
+                          + (" AND d%d.value NOT NULL" % (i,))
+                          for i in range(len(definition))]
+        exact_where = [novalue_where[i]
+                       + (" AND d%d.value = ?" % (i,))
+                       for i in range(len(definition))]
+        like_where = [novalue_where[i]
+                      + (" AND d%d.value GLOB ?" % (i,))
+                      for i in range(len(definition))]
+        is_wildcard = False
+        # Merge the lists together, so that:
+        # [field1, field2, field3], [val1, val2, val3]
+        # Becomes:
+        # (field1, val1, field2, val2, field3, val3)
+        args = []
+        where = []
+        for idx, (field, value) in enumerate(zip(definition, key_values)):
+            args.append(field)
+            if value.endswith('*'):
+                if value == '*':
+                    where.append(wildcard_where[idx])
+                else:
+                    # This is a glob match
+                    if is_wildcard:
+                        # We can't have a partial wildcard following
+                        # another wildcard
+                        raise errors.InvalidGlobbing
+                    where.append(like_where[idx])
+                    args.append(value)
+                is_wildcard = True
+            else:
+                if is_wildcard:
+                    raise errors.InvalidGlobbing
+                where.append(exact_where[idx])
+                args.append(value)
+        statement = (
+            "SELECT d.doc_id, d.doc_rev, d.content, count(c.doc_rev) FROM "
+            "document d, %s LEFT OUTER JOIN conflicts c ON c.doc_id = "
+            "d.doc_id WHERE %s GROUP BY d.doc_id, d.doc_rev, d.content ORDER "
+            "BY %s;" % (', '.join(tables), ' AND '.join(where), ', '.join(
+                ['d%d.value' % i for i in range(len(definition))])))
+        return statement, args
+
+    def get_from_index(self, index_name, *key_values):
+        definition = self._get_index_definition(index_name)
+        if len(key_values) != len(definition):
+            raise errors.InvalidValueForIndex()
+        statement, args = self._format_query(definition, key_values)
+        c = self._db_handle.cursor()
+        try:
+            c.execute(statement, tuple(args))
+        except dbapi2.OperationalError, e:
+            raise dbapi2.OperationalError(str(e) +
+                '\nstatement: %s\nargs: %s\n' % (statement, args))
+        res = c.fetchall()
+        results = []
+        for row in res:
+            doc = self._factory(row[0], row[1], row[2])
+            doc.has_conflicts = row[3] > 0
+            results.append(doc)
+        return results
+
+    def _format_range_query(self, definition, start_value, end_value):
+        tables = ["document_fields d%d" % i for i in range(len(definition))]
+        novalue_where = [
+            "d.doc_id = d%d.doc_id AND d%d.field_name = ?" % (i, i) for i in
+            range(len(definition))]
+        wildcard_where = [
+            novalue_where[i] + (" AND d%d.value NOT NULL" % (i,)) for i in
+            range(len(definition))]
+        like_where = [
+            novalue_where[i] + (
+                " AND (d%d.value < ? OR d%d.value GLOB ?)" % (i, i)) for i in
+            range(len(definition))]
+        range_where_lower = [
+            novalue_where[i] + (" AND d%d.value >= ?" % (i,)) for i in
+            range(len(definition))]
+        range_where_upper = [
+            novalue_where[i] + (" AND d%d.value <= ?" % (i,)) for i in
+            range(len(definition))]
+        args = []
+        where = []
+        if start_value:
+            if isinstance(start_value, basestring):
+                start_value = (start_value,)
+            if len(start_value) != len(definition):
+                raise errors.InvalidValueForIndex()
+            is_wildcard = False
+            for idx, (field, value) in enumerate(zip(definition, start_value)):
+                args.append(field)
+                if value.endswith('*'):
+                    if value == '*':
+                        where.append(wildcard_where[idx])
+                    else:
+                        # This is a glob match
+                        if is_wildcard:
+                            # We can't have a partial wildcard following
+                            # another wildcard
+                            raise errors.InvalidGlobbing
+                        where.append(range_where_lower[idx])
+                        args.append(self._strip_glob(value))
+                    is_wildcard = True
+                else:
+                    if is_wildcard:
+                        raise errors.InvalidGlobbing
+                    where.append(range_where_lower[idx])
+                    args.append(value)
+        if end_value:
+            if isinstance(end_value, basestring):
+                end_value = (end_value,)
+            if len(end_value) != len(definition):
+                raise errors.InvalidValueForIndex()
+            is_wildcard = False
+            for idx, (field, value) in enumerate(zip(definition, end_value)):
+                args.append(field)
+                if value.endswith('*'):
+                    if value == '*':
+                        where.append(wildcard_where[idx])
+                    else:
+                        # This is a glob match
+                        if is_wildcard:
+                            # We can't have a partial wildcard following
+                            # another wildcard
+                            raise errors.InvalidGlobbing
+                        where.append(like_where[idx])
+                        args.append(self._strip_glob(value))
+                        args.append(value)
+                    is_wildcard = True
+                else:
+                    if is_wildcard:
+                        raise errors.InvalidGlobbing
+                    where.append(range_where_upper[idx])
+                    args.append(value)
+        statement = (
+            "SELECT d.doc_id, d.doc_rev, d.content, count(c.doc_rev) FROM "
+            "document d, %s LEFT OUTER JOIN conflicts c ON c.doc_id = "
+            "d.doc_id WHERE %s GROUP BY d.doc_id, d.doc_rev, d.content ORDER "
+            "BY %s;" % (', '.join(tables), ' AND '.join(where), ', '.join(
+                ['d%d.value' % i for i in range(len(definition))])))
+        return statement, args
+
+    def get_range_from_index(self, index_name, start_value=None,
+                             end_value=None):
+        """Return all documents with key values in the specified range."""
+        definition = self._get_index_definition(index_name)
+        statement, args = self._format_range_query(
+            definition, start_value, end_value)
+        c = self._db_handle.cursor()
+        try:
+            c.execute(statement, tuple(args))
+        except dbapi2.OperationalError, e:
+            raise dbapi2.OperationalError(str(e) +
+                '\nstatement: %s\nargs: %s\n' % (statement, args))
+        res = c.fetchall()
+        results = []
+        for row in res:
+            doc = self._factory(row[0], row[1], row[2])
+            doc.has_conflicts = row[3] > 0
+            results.append(doc)
+        return results
+
+    def get_index_keys(self, index_name):
+        c = self._db_handle.cursor()
+        definition = self._get_index_definition(index_name)
+        value_fields = ', '.join([
+            'd%d.value' % i for i in range(len(definition))])
+        tables = ["document_fields d%d" % i for i in range(len(definition))]
+        novalue_where = [
+            "d.doc_id = d%d.doc_id AND d%d.field_name = ?" % (i, i) for i in
+            range(len(definition))]
+        where = [
+            novalue_where[i] + (" AND d%d.value NOT NULL" % (i,)) for i in
+            range(len(definition))]
+        statement = (
+            "SELECT %s FROM document d, %s WHERE %s GROUP BY %s;" % (
+                value_fields, ', '.join(tables), ' AND '.join(where),
+                value_fields))
+        try:
+            c.execute(statement, tuple(definition))
+        except dbapi2.OperationalError, e:
+            raise dbapi2.OperationalError(str(e) +
+                '\nstatement: %s\nargs: %s\n' % (statement, tuple(definition)))
+        return c.fetchall()
+
+    def delete_index(self, index_name):
+        with self._db_handle:
+            c = self._db_handle.cursor()
+            c.execute("DELETE FROM index_definitions WHERE name = ?",
+                      (index_name,))
+            c.execute(
+                "DELETE FROM document_fields WHERE document_fields.field_name "
+                " NOT IN (SELECT field from index_definitions)")
+
+
+class SQLiteSyncTarget(CommonSyncTarget):
+
+    def get_sync_info(self, source_replica_uid):
+        source_gen, source_trans_id = self._db._get_replica_gen_and_trans_id(
+            source_replica_uid)
+        my_gen, my_trans_id = self._db._get_generation_info()
+        return (
+            self._db._replica_uid, my_gen, my_trans_id, source_gen,
+            source_trans_id)
+
+    def record_sync_info(self, source_replica_uid, source_replica_generation,
+                         source_replica_transaction_id):
+        if self._trace_hook:
+            self._trace_hook('record_sync_info')
+        self._db._set_replica_gen_and_trans_id(
+            source_replica_uid, source_replica_generation,
+            source_replica_transaction_id)
+
+
+class SQLitePartialExpandDatabase(SQLiteDatabase):
+    """An SQLite Backend that expands documents into a document_field table.
+
+    It stores the original document text in document.doc. For fields that are
+    indexed, the data goes into document_fields.
+    """
+
+    _index_storage_value = 'expand referenced'
+
+    def _get_indexed_fields(self):
+        """Determine what fields are indexed."""
+        c = self._db_handle.cursor()
+        c.execute("SELECT field FROM index_definitions")
+        return set([x[0] for x in c.fetchall()])
+
+    def _evaluate_index(self, raw_doc, field):
+        parser = query_parser.Parser()
+        getter = parser.parse(field)
+        return getter.get(raw_doc)
+
+    def _put_and_update_indexes(self, old_doc, doc):
+        c = self._db_handle.cursor()
+        if doc and not doc.is_tombstone():
+            raw_doc = json.loads(doc.get_json())
+        else:
+            raw_doc = {}
+        if old_doc is not None:
+            c.execute("UPDATE document SET doc_rev=?, content=?"
+                      " WHERE doc_id = ?",
+                      (doc.rev, doc.get_json(), doc.doc_id))
+            c.execute("DELETE FROM document_fields WHERE doc_id = ?",
+                      (doc.doc_id,))
+        else:
+            c.execute("INSERT INTO document (doc_id, doc_rev, content)"
+                      " VALUES (?, ?, ?)",
+                      (doc.doc_id, doc.rev, doc.get_json()))
+        indexed_fields = self._get_indexed_fields()
+        if indexed_fields:
+            # It is expected that len(indexed_fields) is shorter than
+            # len(raw_doc)
+            getters = [(field, self._parse_index_definition(field))
+                       for field in indexed_fields]
+            self._update_indexes(doc.doc_id, raw_doc, getters, c)
+        trans_id = self._allocate_transaction_id()
+        c.execute("INSERT INTO transaction_log(doc_id, transaction_id)"
+                  " VALUES (?, ?)", (doc.doc_id, trans_id))
+
+    def create_index(self, index_name, *index_expressions):
+        with self._db_handle:
+            c = self._db_handle.cursor()
+            cur_fields = self._get_indexed_fields()
+            definition = [(index_name, idx, field)
+                          for idx, field in enumerate(index_expressions)]
+            try:
+                c.executemany("INSERT INTO index_definitions VALUES (?, ?, ?)",
+                              definition)
+            except dbapi2.IntegrityError as e:
+                stored_def = self._get_index_definition(index_name)
+                if stored_def == [x[-1] for x in definition]:
+                    return
+                raise errors.IndexNameTakenError, e, sys.exc_info()[2]
+            new_fields = set(
+                [f for f in index_expressions if f not in cur_fields])
+            if new_fields:
+                self._update_all_indexes(new_fields)
+
+    def _iter_all_docs(self):
+        c = self._db_handle.cursor()
+        c.execute("SELECT doc_id, content FROM document")
+        while True:
+            next_rows = c.fetchmany()
+            if not next_rows:
+                break
+            for row in next_rows:
+                yield row
+
+    def _update_all_indexes(self, new_fields):
+        """Iterate all the documents, and add content to document_fields.
+
+        :param new_fields: The index definitions that need to be added.
+        """
+        getters = [(field, self._parse_index_definition(field))
+                   for field in new_fields]
+        c = self._db_handle.cursor()
+        for doc_id, doc in self._iter_all_docs():
+            if doc is None:
+                continue
+            raw_doc = json.loads(doc)
+            self._update_indexes(doc_id, raw_doc, getters, c)
+
+SQLiteDatabase.register_implementation(SQLitePartialExpandDatabase)